1. Field of the Invention
The present invention relates to a converter and a discharge-lamp operating apparatus using the converter used to operate a discharge lamp.
2. Description of the Related Art
FIGS. 1 and 2 schematically show a discharge-lamp operating apparatus according to the prior art to operate such discharge lamp as a fluorescent lamp.
The outer case 10 of the conventional discharge-lamp operating apparatus is made of metal, which is constructed by detachably combining the upper case member 12 and the lower case member 14 so that they form an approximately-square tube.
On the inner surface of the lower wall of the lower case member 14, several supporting posts 16, which are cut out from the lower wall and bent inwardly, are arranged.
The printed circuit board 18 is supported along the inner surface of the lower wall by these supporting posts 16 so that the board 18 is separated from the inner surface. The transformer 20 as a magnetic equipment having a core, the switching element 22 comprising such as transistors, and other various electronic parts 24 are installed on the upper surface of the printed circuit board 18. The predetermined wiring patterns are printed on the lower surface of the printed circuit board 18.
The transformer 20, the switching element 22, and other various electronic parts 24 are passed at their downwardly orientated terminals through several through-holes formed at the predetermined positions on the printed circuit board 18, and are secured to the printed circuit board 18 by soldering the downward ends of the terminals to the predetermined positions of the wiring patterns on the lower surface of the printed circuit board 18, so that they comprise a discharge-lamp operating circuit.
The insulating paper 26 is attached to the inner surface of the lower wall of the lower case member 14 in order to assure electrical insulation between the inner surface and the wiring patterns on the lower surface of the printed circuit board 18 arranged closely to the inner surface.
Assurance of electrical insulation between the upper case member 12 and the transformer 20, switching element 22, and other various electronic parts 24 on the upper surface of the printed circuit board 18 is achieved by keeping the distance between them at a predetermined value or more.
The longitudinal ends of the printed circuit board 18 extend beyond the range covered with the upper wall of the upper case member 12. The input terminal block 28 having several terminals 28a for inputting to the discharge lamp operating circuit from a power source (not illustrated) is secured to one of the ends of the printed circuit board 18, and the output terminal block 30 having several terminals for outputting to a fluorescent lamp (not illustrated) form the discharge-lamp operating circuit is secured to the other of the both ends.
In the conventional discharge-lamp operating apparatus configured as mentioned above, the outer case 10 has a large height because the upper wall of the upper case member 12 must be located above the transformer 20, switching element 22, and other various electronic parts 24 on the upper surface of the printed circuit board 18 for a predetermined distance or more in order to assure electrical insulation.
In addition, in order to prevent various electronic parts 24 from being malfunctioned by heat generated from the transformer 20 and switching element 22 while the discharge-lamp operating apparatus is operating, the above-mentioned conventional discharge-lamp operating apparatus has to use the large transformer 20, switching element 22, and various electronic parts 24, each having large heat capacity.
Thus, the above reason causes the height of the outer case 10 to increase and prevents the price of the discharge-lamp operating apparatus from decreasing.
Therefore, it is difficult to decrease the thickness of the luminaire using the above-mentioned conventional discharge-lamp operating apparatus and decrease the price of the luminaire.
Moreover, the above-mentioned conventional discharge-lamp operating apparatus has relatively large natural-oscillation length of the printed circuit board 18 because the printed circuit board 18 is supported to the inner surface of the lower wall of the lower case member 14 by only several supporting posts 16 formed on the lower wall of the lower case member 14. Therefore, beats, generated in the printed circuit board 18 by the vibration generated from the transformer 20 while the discharge-lamp operating apparatus is operating, are easily increased.